Protesters in Pittsburgh are demanding answers from the city's mayor after an activist was abducted by plainclothes officers into an unmarked van on Saturday.
A video captured the moments after the protester, Matthew Cartier, 25, was pulled into an unmarked van by the city's police.
Mr Cartier was helping to lead the protest at the time of his arrest.
The next day, Pittsburgh Mayor Bill Peduto held a press conference during which a city police incident commander explained the department's rationale for abducting the protester.
"Watching these tactics, [Mr Cartier's] refusal to cooperate and the information that we were given ... we decided to effect a low visibility arrest of the individual because when high visibility stuff takes places with these marches, it tends to attract a crowd and incite them further," the police commander said. "So we decided low visibility was the best way to do it and it also gave us the ability if he suddenly started cooperating to call the arrest off."
Ryan Deto, a reporter for the Pittsburgh City Paper, obtained the criminal complaint against Mr Cartier, which police used to justify their arrest.
"According to the criminal complaint, Pittsburgh Police's rational for rolling up & arresting Matthew in an unmarked van, was that he 'startled drivers' because he was marshaling the protest," Mr Deto wrote on Twitter.
Mr Cartier was marching with the youth activist organisation Black, Young, and Educated, which has led 11 demonstrations in the city in recent weeks. He said the police lured him towards the van by pretending to be lost and in need of directions.
"The Pittsburgh Police approached the bike perimeter in an unmarked van and lured me closer by pretending to need directions around the march," he wrote on Twitter. "@billpeduto answer for this you rat."
Mr Peduto said the video of the arrest made him "uncomfortable," according to CBS affiliate KDKA 2 Pittsburgh.
"When we look at pop-out as a tactic, especially with officers who are in plain clothes, we have to examine when that is appropriate," Mr Peduto said. "We have to have an understanding if that is a tactic that should be utilised for a protest, and if so, when. And if when, why."
In a tweet on Saturday, Mr Peduto suggested that a protest blocking traffic was in violation of the city's code.
"The right to assemble is a guaranteed right, the right to shut down public streets, is a privilege," he wrote. "That privilege is sanctioned by laws and codes. In Pittsburgh, we worked w ACLU & CPRB to create our codes."
The ACLU of Pennsylvania confirmed that they worked on the codes alongside the city's leadership, but also said it appeared the officers were in violation of those guidelines.
"However, based on eyewitness accounts, the arresting officers were in clear violation of their own guidelines. According to those who were there, the law enforcement officers involved made no effort to work with protest leaders to clear the area and gave no clear dispersal order," an ACLU spokesperson wrote on Twitter. "Instead, they tricked a protest leader to approach them and then whisked him away. The ACLU of Pennsylvania has never suggested that the snatch-and-stash arrest of a peaceful demonstrator is ever acceptable."
Police officials claim they warned Mr Cartier "several times" not to block intersections during the group's march.
Mr Cartier said that the individual sitting in the passenger seat grabbed him as several other men "sprang out of the back of the van heavily armed" and arrested him. He said he was searched and then taken to the county jail.
"The actions taken by the city's police department and tacitly endorsed by @billpeduto are horrifying. Every protester must now live in fear of getting grabbed by the police in such a violent and terrifying manner," he said.
Mr Cartier is being charged with failure to disperse, disorderly conduct and obstructing highways and other public passages. He was initially facing five total charges, which included risking a catastrophe and being an unauthorized person directing traffic, but the city dropped those charges.
Mr Cartier's legal representation, attorney Lisa Middleman, issued a statement on social media condemning the city's actions.
"I have no intention of trying my client's case in the court of public opinion, but I am disturbed by leadership's failure to admit the errors in judgement and tactics that are designed to have a chilling effect on the exercise of civil liberties and constitutional rights," she wrote. "If we are to have any meaningful dialogue about the future of policing in this city and county, a better effort must be made to address the concerns of the community. Demanding communication under threat of arrest is not an honest effort to encourage dialogue."
She said that the leadership's failure to "meaningfully engage with the actual people whose day-to-day lives are impacted by our broken legal system" is why so many people fear and distrust the police.
"The responsibility to change that lies with our elected and appointed officials," she wrote. "And the mayor's 'serious concerns' must result in serious action."
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